Developing an understanding of information processing in the olfactory system has proven to be a difficult task. Research on the relationship between physiological activity in olfactory bulb and the perception of odor quality has suffered from a lack of information about the odor world of the experimental animal. The experiments proposed here employ integrated methods to compare physiological activity, measured using single unit recording and odors are coded by olfactory bulb activity. Using behavioral and physiological methods in combination, specific issues can be examined that cannot be addressed using either method alone. The proposal addresses two specific aims: 1) to determine whether odors that cannot be discriminated in a behavioral task elicit similar activity patterns in single olfactory bulb output neurons, and 2) to determine the significance of the spatial patterns of response of populations of mitral/tufted cells in encoding odor quality. The results of these experiments will contribute significantly to the understanding of information processing in the olfactory system.